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UTCTEA1062AN View Datasheet(PDF) - Unisonic Technologies

Part NameDescriptionManufacturer
UTCTEA1062AN LOW VOLTAGE TELEPHONE TRANSMISSION CIRCUIT WITH DIALLER INTERFACE UTC
Unisonic Technologies UTC
UTCTEA1062AN Datasheet PDF : 13 Pages
1 2 3 4 5 6 7 8 9 10 Next Last
UTC TEA1062N / TEA1062AN
LINEAR INTEGRATED CIRCUIT
FUNCTIONAL DESCRIPTION
Supply: VCC, LN, SLPE, REG and STAB
Power for the UTC TEA1062N/TEA1062AN and its
peripheral circuits is usually obtained from the
telephone line. The IC supply voltage is derived from
the line via a dropping resistor and regulated by the
UTC TEA1062N/TEA1062AN,The supply voltage Vcc
may also be used to supply external circuits e.g.
dialling and control circuits. Decoupling of the supply
voltage is performed by a capacitor between Vcc and
VEE while the internal voltage regulator is decoupled
by a capacitor between REG and VEE. The DC current
drawn by the device will vary in accordance with
varying values of the exchange voltage(Vexch), the
feeding bridge resistance(Rexch) and the DC resistance
of
the telephone line(Rline). The UTC
TEA1062N/TEA1062AN has an internal current
stabilizer operating at a level determined by a 3.6kΩ
resistor connected between STAB and VEE( see
Fig.8). When the line current(Iline) is more than 0.5 mA
greater than the sum of the IC supply current ( Icc) and
the current drawn by the peripheral circuitry connected
to VCC(lp) the excess current is shunted to VEE via LN.
The regulated voltage on the line terminal(VLN) can be
calculated as:
VLN=Vref+ISLPE*R9 or;
VLN=Vref+[(Iline – ICC - 0.5*10-3A)Ip]*R9
where:Vref is an internally generated temperature
compensated reference voltage of 3.7V and R9 is an
external resistor connected between SLPE and VEE. In
normal use the value of R9 would be 20. Changing
the value of R9 will also affect microphone gain, DTMF
gain,gain control characteristics, side tone level,
maxmimum output swing on LN and the DC
characteristics (especially at the lower voltages). Under
normal conditions, when ISLPE>=ICC+0.5mA +Ip, the
static behaviour of the circuit is that of a 3.7V regulator
diode with an internal resistance equal to that of
R9.In the audio frequency range the dynamic
impedance is largely determined by R1.Fig.3 shows
the equivalent impedance of the circuit.
Microphone inputs(MIC+ and MIC-) and
gain pins (GAS1 and GAS2)
The UTC TEA1062N/TEA1062AN has symmetrical
inputs. Its input impedance is 64k(2*32k) and its
voltage gain is typically 52 dB (when R7=68k.see
Fig.13). Dynamic, magnetic, piezoelectric or electret
(with built-in FET source followers) can be used.
Microphone arrangements are illustrated in Fig.10. The
gain of the microphone amplifier can be adjusted
between 44dB and 52dB to suit the sensitivity of the
transducer in use. The gain is proportional to the value
of R7 which is connected between GAS1 and GAS2.
Stability is ensured by the external capacitors, C6
connected between GAS1 and SLPE and C8
connected between GAS1 and VEE. The value of C6
is 100pF but this may be increased to obtain a
first-order low-pass filter. The value of C8 is 10 times
the value of C6. The cut-off frequency corresponds to
the time constant R7*C6.
Mute input (MUTE)
A LOW(UTC TEA1062N is HIGH) level at MUTE
enables DTMF input and inhibites the microphone
inputs and the receiving amplifier inputs; a HIGH(UTC
TEA1062N is LOW) level or an open circuit does the
reverse. Switching the mute input will cause negligible
clickis at the telephone outputs and on the line. In case
the line current drops below 6mA(parallal opration of
more sets) the circuit is always in speech condition
independant of the DC level applied to the MUTE input.
Dual-tone multi-frequency input (DTMF)
When the DTMF input is enabled dialling tones may
be sent onto the line. The voltage gain from DTMF to
LN is typically 25.5dB(when R7=68k) and varies with
R7 in the same way as the microphone gain. The
signalling tones can be heard in the earpiece at a low
level(confidence tone).
Receiving amplifier (IR,QR and GAR)
The receiving amplifier has one input (IR) and a
non-inverting output (QR). Earpiece arrangements are
illustrated in Fig.11. The IR to QR gain is typically 31dB
(when R4=100k). It can be adjusted between 20 and
31dB to match the sensitivity of the transducer in use.
The gain is set with the value of R4 which is connected
between GAR and QR.The overall receive gain,
between LN and QR, is calculated by substracting the
anti-sidetone network attenuation (32dB) from the
amplifier gain. Two external capacitors, C4 and C7,
ensure stability. C4 is normally 100pF and C7 is 10
times the value of C4. The value of C4 may be
increased to obtain a first-order low-pass filter.The
UTC UNISONIC TECHNOLOGIES CO., LTD. 6
QW-R108-011,A
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